Indicator light for hobbing machines



July 25, 1950 w. s. BROWER INDICATOR LIGHT FOR uossmc MACHINES 2 Sheeis-Sheet 1 Filed Jan. 11, 1949 2 Sheets-Sheet 2 W. S. BROWER INDICATOR LIGHT FOR HOBBING MACHINES July 25, 1950 Filed Jan. 11, 1949 f 71716 712 07 ill tam Zfirgwef Patented July 25, 1950 INDICATOR LlGI-IT FDR HOBBING MACHINES William S.

Brewer, Muncie, Ind., assignor to Borg-Warner Corporation, Chicago, 111., a corporation of Illinois Application January 11, 1949, Serial No. 70,225

7 Claims.

This invention relates to hobbing machines and more particularly to a device for indicating whether or not the hob has been shifted with respect to the work piece at the end of a cycle of operation so as to present a different cutting surface to the next work piece in the following a less worn cutting surface to the next work piece and thereby to distribute the wear evenly over the hob. While this shifting may be performed manually by the hobbing machine operator, be-

cause of the desirability of efiiciently utilizing the a full working surface of the hob by uniformly distributing the wear over the hob and because of the diificulty of doing this manually, automatic means are preferably provided for shifting the hob at the end of each cycle of operation. It has been found in practice that while such automatic detailed description taken in conjunction with the drawings wherein:

In the drawings:

Fig. 1 is a fragmentary end view, partly in section showing a hobbing machine having a hob shift indicator associated therewith in accordance with this invention;

Fig. 2 is a view of the portion of the hobbing machine shown in Fig. 1, taken from the right side thereof as viewed in Fig. 1; and

Fig. 3 is an enlarged sectional view taken along the line 3-3 of Fig. 1.

Referring now to the drawings and particularly to Figs. 1 and 2 thereof wherein to simplify description and to facilitate a rapid understanding of the invention only that portion of a conventional automatic gear bobbing machine is illustrated which is directly pertinent to the presshifting meansmay be made to provide fairly" consistent operation, it is desirable to provide also a positive indication to the operator that the hob has been shifted and that the machine is ready to be reloaded and to begin the next cycle of operation.

An object of the present invention isto provide a simple, efficient, and economical hob shift 1 indicator arranged to provide a visual signal as to whether or not the hob has been shifted at the hob axially atthe end of a cycle of operation, a,

hob shift indicator is provided comprising a micro-switch and a cam for actuating the microswitch, the cam being arranged to rotate witha lead screw utilized for shifting the hob. The

ent invention, a hob i0 is shown fixed on a driving shaft II which is rotatably supported by suitable supportin means indicated at l2, which means are mounted on a carriage l3. Suitable gearing (not shown) is also keyed to the shaft I l for rotating the hob H) with respect to a work piece indicated generally at IS. The work piece l5 may comprise as shown a plurality of stacked, gear blanks.

It will be understood that in the course of operation of the hobbing machine the work piece is simultaneously rotated and advanced vertically, as viewed in Fig. 1, with respect to the hole Hi, while the hob H3 is rotated rapidly about its axis in a fixed position. Thus only a very small portion of the cutting surface of the hob is utilized in cutting one group of gear blanks.

To distribute the wear uniformly over the surface of the hob it is necessary to shift the hob axially a short distance betweencycles of operation. In order to permit this axial adjustment and to allow movement of the hob transversely with respect to the position of the work piece, the hob carriage I3 is slidably dovetailed into a bed IE and is arranged to be moved with respect cam is rotated only if the hob is shifted; conse-;-

quently, the micro-switch which controls a pair of lamps of different colors is actuated only if the hob is shifted to light one of the lamps and to extinguish the other of the two lamps. Means are'also provided for returning the cam to dwell to the bed by a lead screw [1. The lead screw ll is rotated a predetermined angular distance at 'theend of each cycle of operation of the'hobbing machine so as to advance the'hob transversely with respect to the plane of the work piece and thereby to present a lessworn cutting surface to the work piece, thus distributing the wear evenly over the hob. A suitable mechanism for accomplishing this intermittent actuation of: the lead screw is that illustrated in Figs. 1 and 2 and comprises a gear is keyed to the lead screw l1 adjacent its left end, as viewed in Fig. 2, and

meshing with an intermediate spur gear l9 fixed to freely rotatable shaft 20. The shaft 20 is rotated by a third gear 2| keyed thereto and meshing with a fourth gear 22 keyed to a shaft 23 which in turn is rotated by gear 24 through a clutcharrangement 25 of generally conventionaldesign, driving a gear 26 keyed to the clutch shaft 27, the gear 25 meshing with the gear 22. The clutch 25 comprises an outer ring gear 28 meshing with a rack 29 which is reciprocated by a hydraulically energized plunger 31 operated through the control system of the hobbing machine at the end of each cycle of the hobbing operation. Inner cam member 32 of the clutch 25 is keyed to the shaft 27 and comprises an octagonal disc and a. plurality of roller pins 33 are disposed between the periphery of the disc 32 and the inner wall of the ring gear 28 so that when the hydraulic plunger 3| is actuated to move the. rack. 28 the clutch '25 engages and through the above described train of gears l8, l9, 2|, 22 and 24 the lead screw I! is angularly displaced to advance the hob carriage l3 with respect to the bed It. The structure and operation so far described is conventional and since it is not claimed as part of, the present invention, no more detailed description thereof is believed ,warranted.

In accordance with the present invention in order to provide a positive indication that the hob has been shifted at the conclusion of a cycle of operation, an indicatormechanism designated generally at 35 isprovided'and is arranged to be operated through the rotation of the lead screw and maybe-mounted in a suitably conspicuous place on or adjacent the hobbing machine. The lamp 3! may be red and indicates when lighted that the hob has been shifted, whereas the lamp :38 may be white and indicates when lighted that the hob has not been shifted or that the machine is in cycle.

trolled by rotation of a cam which is frictionallysupported on. astub-shaft .48 by a split...

bushing 41. The stub-shaft 46 is supported at 1 its left end, as viewed in Fig. 2, in a sleeve bearing 48, fixed in a cup-shaped housing 49 which is mounted on the plate 36. The cam 45 is arformed' in the plate'35 and is squared to engage a complementarily squared collar 5| provided at "the right end of the shaft 46.

"ranged to be rotated by the lead screw !1, the left end of which extends through aperture 50 The micro-switch 39 is provided with a springpressed plunger 52; the tip of which bears against the periphery of the cam 45 and when the lamp "38 is lighted extends into a notch 53 formed in the cam 45. Rotation of the cam from this position pushes the plunger 52 back, as the tip of the plunger rides out of the notch 53; this causes the lamp 31 to be. lit and the lamp 38' to I be extinguished.

' Since it is desired that the indicator be operated 'only'at the conclusion of a cycle of operation, and also to prevent false operation of the [5 indicator such as might be occasioned by a slight movement of the lead screw I! in the course of the hobbing cycle itself, this invention also includes means for preventing rotation of the cam 45 except at the termination of the hobbing cycle. This means comprises a plunger 54 which is adapted to be received in a V-shaped notch 55 formed in the periphery of the cam 45. In the embodiment illustrated the plunger 54 is actuated by a hydraulic mechanism indicated generally at 56 and including a hydraulic line 57 for retracting the plunger and a second hydraulic line 53 for advancing the plunger. However, it will be understood that any other type of means for advancing and retracting the plunger might well be substituted, such for example, as a solenoid. In the embodiment illustrated, during the operation of the bobbing machine pressure is supplied through the hydraulic line 58 to maintain the plunger 54 in the notch 55 in the cam 45, the pressure being supplied from suitable pressure control apparatus operating in timed relation to the operation of the hobbing machine, thus preventing rotation of the cam 45. Under these circumstances, the cam 45 because of the split bushing support 41 slips relatively to the shaft 46.

At the conclusion of a cycle of operation of the hobbing machine, pressure is removed from the hydraulic line 58 and supplied through the hydraulic line 5'! to retract the plunger 54. The cam 45 is now free to rotate with the shaft I1, and if the shaft I? is rotated at this time through the actuation of the hydraulic plunger 3! and the above described gear train to advance the hob, then the cam 45 will be rotated to move the micro-switch plunger 52 out of the notch 53 and thereby energize the lamp 31.

The cam 45 is permitted to rotate in either direction, in accordance with the direction of rotation of the lead screw 11, a distance limited by the length of the recess 60 formed in the periphery of the cam 45 opposite the position of the notch 55 and approximately removed from the position of notch 53. A stop pin 6! extends across this recess, the pin 6| being carried by the cupshaped housing 49 and the end plate 36, and when the micro-switch plunger 52 is in. the notch 53, at which time the hydraulic plunger 54 is in the notch 55, the pin 6| is positioned substantially at the middle of the recess 60, that is midway between the ends thereof. When the cam 45 is rotated however by the turning of the lead screw H and the shaft 46, the rotation of the cam is stopped when the pin 6] engages either end of the recess 60, The length of the recess 60 is selected not only to permit a suflicient rotation of the cam 45 to actuate the micro-switch but also to limit the rotation of the cam to an amount from which the hydraulic plunger 54 by engaging on of the V-shaped sides of the notch 55 may return the cam 45 to starting position, that is to the position where the micro-switch plunger 52 is received in the notch 53. The degree of frictional engagement of the split bushing 41 is controlled by a radially disposed threaded member 62, which is threaded in the cam 45 and the inner end of which bears against a side of the split bushing 41. By threading the member 62 into or out of the cam 45 the frictional engagement may be increased or decreased as required.

In the event the bobbin-g machine has failed to advance the hob at the conclusion of a cycle of operation, means are provided in accordance with this invention whereby the operator may manually position the carriage l3 and hob it as required. Referring to Figs. 2 and 3 it will be seen that the left end of stub shaft 46 is extended beyond the housing 49 and squared to provide a head 63 to which a crank, not shown, may readily be fitted by the operator. Rotation of the stub shaft 45 will cause rotation of the lead screw I! and movement of the carriage l3.

Where herein the various parts of the hobbing machine of this invention have been referred to as being located in a right or a left position, it will be understood that this is done solely for the purpose of facilitating description and that the references relate only to the relative position of the parts as shown in the accompanying drawings.

What is claimed is:

1. In a hobbing machine, means for shifting the hob, a shaft rotatable with said hob shifting means, a cam frictionally supported on said shaft, a switch associated with said cam and arranged to be operated by rotation of the cam, signaling means controlled by said switch and arranged to provide one indication in one position of said cam and a second distinctive indication when said cam has been rotated from said one position, and releasable locking means associated with said cam for preventing rotation of the cam except at the conclusion of a hobbing cycle.

2. A hobbing machine according to claim 1 wherein the means for preventing rotation of the cam comprises a hydraulically actuated plunger adapted to engage the periphery of said cam.

3. A hobbing machine according to claim 1 wherein means are provided for limiting the degree of rotation of the cam from said one position.

4. A hobbing machine in accordance with claim 1 including means for limiting the degree of rotation of the earn from said one position, said cam having a notch formed in the periphery thereof, and a plunger adapted to engage the sides of the notch for returning the cam to said one position.

5. A hobbing machine in accordance with claim 1 wherein means are provided for limiting the degree of rotation of the cam from said one position, said cam having a wedge-shaped notch formed in the periphery thereof, a plunger arranged to enter said notch to prevent rotation of said cam, and means for rotating said shaft independently of the locking action of said Plunger with respect to said cam.

6. A hobbing machine in accordance with claim 1 wherein means are provided for adjusting the degree of frictional engagement between said shaft and said cam.

7. A hobbing machine in accordance with claim 1 including a split bushing for supporting said cam on said shaft, and threaded member carried by said cam and arranged to engage the split bushing to adjust the degree of frictional engagement between said shaft and said cam,

WILLIAM S. BROWER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 564,168 Tower July 14, 1896 887,805 Higgins May 19, 1908 FOREIGN PATENTS Number Country Date ,5 1 Great. Britain an," Aug. 9, 193% 

